Kiln



Aug. 13, 1968 D, E. SANDBROOK 3,396,953

KILN

Filed Dec. 22, 1965 4 Sheets-Sheet l Alfa/nay Aug' 13, 1968 D. E. SANDBROOK 3,396,953

KILN

Filed Dec. 22, 1965 4 Sheets-Sheet 2 Il TER/ L FROM SCREW 0IIVEYOR INVENTO? DEAN E. SNDBROUK Allorncy Aug. 13, 1968 D. E. SANDBROOK KILN 4 Sheets-Sheet 3 F1 led Dec. 22, 1965 u E ne H susa fsm A L MATERIAL HEATED MATERIAL HEATED y' il HEArEo MATER/AL,

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mi UPP [NVE/V TOR DEA/V E. SANDBROOI( Affornay DV E. SANDBROOK 3,396,953

KILN

4 Sheets-Sheet 4 f0 DUST COLLETOR Aug. 13, 1968 Filed Dec.

w M i Q \k Harney United States Patent O 3,396, 53 KILN Dean E. Sandbrook, Norwalk, Conn., assgnor to United States Steel Corporation, a corporation of Delaware Filed Dec. 22, 1965, Ser. No. 524,649 13 Claims. (Cl. 263-33) ABSTRACT F THE DISCLOSURE This improved rotary inclined kiln has an outer inclined member rotatable on the frame. An inner inclined member is disposed within the outer inclined member. A screw member is on one of the outer inclined member and the inner inclined member, the screw member and the one form a conveying and heat exchanging means. Feed means are disposed adjacent the outer inclined member and the inner inclined member for introducing the material into the one at the low hot end of the kiln. Heat producing means are disposed adjacent the low hot end for introducing heat to the outer inclined member and the inner member. The conveying and heat exchanging means are operable to move the material to the upper relatively cooler end of the one and to function as a heat exchanger between the material and the heat. The other of the outer inclined member and the inner inclined member is adapted to receive the raw material at the upper relatively cooler end an-d move the material to the low hot end.

This invention relates to rotary kilns for the processing of lime, brick cement and the like, for the direct reduction of iron ore to pig iron, for sintering, nodulizing, briquetting and pelletizing agglomerates and more particularly to an improved rotary kiln for calcining or burning raw materials into marble-like clinker.

Heretofore, conventional rotary kilns for burning, roasting, sintering and drying conventional materials, such as cement, lime, and expanded aggregates are of the type shown in the following patents:

U.S. Patent No. Inventor Issu(l llate 865,110 G. F. Knapp Sept. 3, 1907. 1,793,499 l. T. Lindliard Fel). 24, 1931. 2,3l9,673 I ll. French May 1S, 1943. 2,687,290 J. M. (iuroutte, et al Aug. 24, 1954. 3,097,833 F. J. Harris, et al July 1G, 1963.

Such inclined rotary kilns are provided with a refractory brick lining and a cylindrical steel shell and are used for calcining raw materials into cement clinker. The raw material is fed continuously into the higher end of the cylindrical kiln and such raw material moves co-ntinuously down the slowly rotating inclined kiln toward the discharge end. The heat for calcining the raw material is provided by the firing of a material, such as pulverized coal, natural gas or fuel oil, into the discharge end of the kiln in an upward direction opposite to the downward direction of movement of the raw materials in such kiln.

Such conventional kilns utilize large quantities of fuel to achieve the approximate 28000 F. temperature adjacent the discharge end of the kiln which discharge temperature is required to cause the desired chemical changes to take place in the raw materials (i.e. removal of moisture, carbon dioxide and other gases) and to form marble-like clinker by fusion of the chemically transformed raw materials. Because of their exposed structure conventional kilns are thermally inefficient due to heat losses through the steel shell and to heat losses at the entrance end and discharge end thereof due to conduction, radiation and convection. A further disadvantage of conventional kilns is the short operative life of the structural shell resulting from the intense heat and high temperatures.

It is the general object of the present invention to avoid lll dill

3,396,953 Patented Aug. 13, 1968 Fice and overcome the foregoing and other difficulties of and objections to prior art practices by the provision of an improved rotary kiln of the heat exchanger type, which rotary kiln:

(a) Has a substantially increased thermal eiciency;

(b) Has a longer operative life than conventional rotary kilns:

(c) Reduces the fuel consumption per barrel of clinker produced;

(d) Increases the productive output of the rotary kiln;

(e) Has substantially smaller space requirements than conventional kilns;

(f) Reduces substantially the exhaust temperatures in the kiln back housing thereby providing substantial fuel savings;

(g) Is simple and rugged in structure and easy to maintain.

The aforesaid objects of the present invention, and other objects which will become apparent as the description proceeds, are achieved by providing an improved rotary inclined kiln for heat treating a material and having a low hot end and an upper relatively cooler end and a frame. This improved rotary inclined kiln has an outer inclined member rotatable on the frame. An inner inclined member is disposed within the outer inclined member. A screw member is on one of the outer inclined member and the inner inclined member, the screw member and the one form a conveying and heat exchanging means. Feed means are disposed adjacent the outer inclined member and the inner inclined member for introducing the material into the one at the low hot end of the kiln. Heat producing means are disposed adjacent the low hot end for introducing heat to the outer inclined member and the inner member. The conveying and heat exchanging means are operable to move the material to the upper relatively cooler end of the one and to function as a heat exchanger between the material and the heat. The other of the outer inclined member and the inner inclined member is adapted t-o receive the raw material at the upper relatively cooler end and move the material to the low hot end.

For a better understanding of the present invention reference should be had to the accompanying drawings, wherein like numerals of reference indicate similar parts throughout the several views and wherein:

FIGURE l is a side elevational view of the improved rotary kiln of the present invention and showing the drive means on the outer shell.

FIGURE 2 is an enlarged fragmentary vertical sectional view of the drying and preheating zone of the rotary kiln of the invention showing the screw member of the conveying and heat exchanging means on the inner member `and omitting the raw material for the sake of clarity;

FIGURE 3 is a vertical sectional view taken along the line lll- III of FIGURE 2 in the direction of the arrows;

FIGURE 4 is a vertical sectional view taken along the line IV-IV of FIGURE 2 in the direction of the arrows but omitting the raw material for the sake of clarity;

FlGURE 5 is a fragmentary vertical sectional view of an alternative embodiment of the conveying and heat exchanging means ofthe rotary kiln showing the screw member on the outer member but omitting the raw material for the sake of clarity;

FIGURE 6 is a vertical sectional view taken `along the line VI-Vl of FIGURE 5 in the direction of the arrows;

FIGURE 7 is another vertical sectional view taken along the line VII- VII of FIGURE 5 in the direction of the arrows;

FIGURE 8 is a fragmentary vertical sectional view of another alternative embodiment of the rotary kiln showing the screw member provided with drive means `but omitting the raw material for the sake of clarity; and

FIGURE 9 is also a vertical sectional view of a further embodiment of the rotary kiln showing the inner shell provided with drive means and omitting the raw material for the sake of clarity.

Although the principles of the present invention are broadly applicable to rotary kilns for the processing of lime, brick, cement and the like, for the direct reduction of iron ore to pig iron, for sintering. nodulizing, briquetting and pelletizing agglomeraties, the present invention is particularly adapted for use for calcining or burning raw materials into a marble-like clinker and hence it has been so illustrated and will be so described.

With specific reference to the form of the present invention illustrated in the drawings. `and referring particularly to FIGURES 1, 2, a rotary inclined kiln of this invention is indicated generally by the reference number 10 and is employed for heat treating a material, such as kiln feed.

As shown in FIGURE l, the rotary inclined kiln I0 has an outer inclined member. such as outer cylindrical shell 12 (FIGURES 1-4). which outer shell 12 extends from a feed house 14 (FIGURE 1) to a burner building 16 (FIGURE 1). Such outer shell 12 is provided at spaced intervals with reinforcing sleeves 18 (FIGURE l) and tires 20 which ride On rolls 22 mounted on a frame 24 of the kiln l0. This outer shell l2 is rotatable in a direction, such as indicated by the arrow in FIGURE I. by drive means. such as girth gear 26 (FIGURE l), pinion gear 28, gear reduction unit 30 and motor 32.

The rotary inclined kiln 10 may be employed to heat treat a material such as calcining raw material 34 (FIG- URES 1. 3). into cement clinker. This raw material 34 is conveyed by a supply means. such as a screw conveyor 36 (FIGURE I), from the feed house 14 into a feed means 38 (FIGURES l-3). disposed adiacent the outer shell 12 in a drying and preheating zone for introduction i of the raw material 34 into the rotary kiln Ill. This raw material or kiln feed 34 may comprise crushed limestone, shale, sand and iron ore.

The feed means 38 may comprise, by way of example` a stationary housing 40 (FIGURES l---3) disposed about the outer shell 12 and having an inlet 39 (FIGURES 2, 3) from the screw conveyor 36. Within the stationary housing 40 are a plurality of spaced scoops 42 (FIGURES 2,3) carried by the outer shell l2. These scoops 42 project into an annulus 44 (FIGURES 2, 3) between the stationary housing 40 and the outer shell 12 and convey raw material 34 (FIGURES l. 3) to an inner inclined member, such as the inner cylindrical shell 46 (FIGURES 1 4). at a low hot end of the preheating and calcining zone or driping and preheating zone.

As shown in FIGURES I4, this inner shell 46 carries a spiral or screw member 48, secured to the inner shell 46, as by welding at 50 (FIGURE 2), or is removably mounted on the inner shell 46 by means of bolts (not shown) but similar to the bolts 50a (FIGURE 5). This inner shell 46 is oatingly suspended from the outer shell 12 at spaced intervals by a plurality of rods 52 (FIG- URES l, 2 and 4), secured at 53 (FIGURES 2,4) on the inner shell 46 and biased by springs 54 (FIGURES I, 2 and 4) against the outer shell12.

This inner shell 46 has a low hot end (FIGURE 2) having a temperature of about 1800D F. adjacent the feed means 38 and an upper relatively cool end in the lefehand portion of FIGURE 2 having a temperature of about 1000 F. The spiral member 48 and inner shell 46 receive the large mass of relatively cool raw material 34 having an ambient temperature of about 40-100 F. at the low hot end. The spiral member 48 and inner shell 46 comprise a conveyor and heat exchanger means 49` (FIGURE 2) and are operable to move the raw matcrial 34 in the direction of the arrows (FIGURE 1) to the upper relatively cool end. Both the inner shell 46 and the spiral member 48 function as a heat exchanger be tween the raw material 34 and the heated gas flow indicated by the arrows in FIGURE 2 during this path of Llll movement. As a result a more efficient operation of the rotary kiln 10 is obtained, the frame 24 is protected from the extreme heat and exhaust temperatures in the back house 14n (FIGURE l) are reduced from about 1600 F. in conventional kilns to about i000o F. the back house 14n (FIGURE I) is disposed adjacent thc upper relatively cooler cnd. has an entrance portion 14H1 provided with a flow cross section greater than the flow cross section ol the exit 12a from the outer shell 12 and provides maximum flow of maximum temperature heated Huid through the outer shell 12, the inner shell 46 and the material 34 therein.

Heat producing means (not shown), such as a conventional burner for tiring either pulverized coal, natural gas, fuel oil, or the like, are disposed in the burner building 16 (FIGURE l) and feed heated gases at a temperature of about 2800o F. into the outer shell 12 and the inner shell 46. The heat producing means or burner building I6 has an exit portion 16a provided with a flow cross section greater than the flow cross section of the entrance 12a] to the outer shell 12 for introducing a maximum flow of maximum temperature heated uid into the outer shell 12 and the inner shell 46.

Referring to FIGURE 2, the raw material 34 drops olf the upper relatively cooler end of the inner shell 46 and moves in the direction of the arrows of FIGURES I, 2 down the outer shell 12 toward the low hot end of the rotary inclined kiln i0. Thereafter. referring to FIGURE l, the raw material 34 passes successively through the burning zone and quenching and discharging Zones ofthe outer shell 12 from which it is transferred as clinker t0 a storage means (not shown).

As shown in Table l below, it has `been found that the improved rotary kiln 10 of this invention provides the following fuel reductions:

The above are typical examples. Each kiln 10 must be considered by itself and the heat exchanger parameter determined on an individual basis. However, fuel economics and increased production of about 10 to 15% can be achieved.

A l'ternrltire embodiments It will be understod by those skilled in the art that alternatively in FIGURES 5, 6 and 7 the spiral or screw member 485 of the conveyor and heat exchanger unit 495 is disposed in the annulus 62 between the outer shell l25 and inner shell 46. Raw material 34 moves to the left as viewed in FIGURE 5 in the annulus 62 and is transferred to the inner shell 46 at the upper cooler end of such outer shell by a transfer means 38a (FIGURES 5, 7), which transfer means 38a is similar to the feed means 38 shown in FIGURE 3 and has vanes 63 (FIGURES 5, 7,) for guiding the raw material 34 into the inner shell 46. The feed means 38a is `modified, as shown in FIGURE 7, to deliver raw material 34 to the annulus 62. The screw member 485 may also be driven by separate drive means (not shown), but similar to the shaft 56, bearings 57 and motor 60 shown in FIGURE 8, provided the reinforcement members S9 (FIGURE 8) are eliminated. Bolts 50a (FIGURE 5) secure the screw members 485 to the outer shell 125.

Alternatively, as shown in FIGURE 8, the spiral or screw member 48B may be provided with drive means, such as the spoked wheel yoke S5 on a shaft 56 extending on a bearing 57 through kiln back housing 14a and the motor 60, so as to cause relative rotative motion between the inner shell 46 and the spiral member 488.

Longitudinal reinforcing members 59 for the spiral member 48a extend from the yoke 55. Rods 52 are threaded into connector 53, which connector S3 is welded to the inner shell 46.

It will be also understood by those skilled in the art that the inner shell 46 (FIGURES 1-4) etc. and the outer shell 12 (FIGURES 1-4) etc. need not be concentrically mounted on the same longitudinal axis but to avoid impacting of the raw material 34 within the kiln .10 (FIG- URES 1-4) etc. such concentric mounting is desirable.

Further the outer shell 12 (FIGURES 1-4) etc. and inner shell 46 (FIGURES l-4) etc. may be polygonal as well as cylindrical in vertical cross section.

Referring to FIGURE 9, the inner shell 469 is journaled in a series of bearing sleeves 64 supported by the rods 52 and is rotated with respect to outer shell 12 by a separate drive means, such as the spoked wheel yoke 559 on shaft 56, bearing 57 and motor 60. Similarly the outer shell 12 may be connected to a drive means, such as the girth gear 26 etc. (FIGURE l) and rotated with respect to the inner shell 469.

It will be recognized by those skilled in the art that the objects of the present invention have been achieved by providing improved inclined rotary kilns (FIGURE 1-4), 105 (FIGURES 5, 6 and 7), 105 (FIGURE 8), 109 (FIGURE 9) which substantially increase the thermal eticiency thereof by about l() to These simple rugged kilns 10 (FIGURES 1-4) etc. are easy to maintain, reduce the fuel consumption about l() to 15%, and increase the productive output therefrom by about the same amount. Such kilns 10 (FIGURES l-4), etc. have substantially smaller space requirements within the mill than conventional kilns and `actually reduce such space requirements by about 15%. In addition, the exhaust temperatures in the kiln back housing 14a (FIGURE 1) etc. are reduced about 600 F. from the temperature of about l600 F, in conventional kilns.

While in accordance with the patent statutes a preferred and alternative embodiment of the present invention has been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.

I claim:

1. A rotary inclined kiln for heat treating a material and having a low hot end and an upper relatively cooler end, said kiln having:

(a) a frame,

(b) an outer inclined member rotatable on said frame,

(c) an inner inclined member disposed within said outer inclined member,

(d) a screw member on one of said outer inclined member and said inner inclined member,

(e) said screw member and said one forming a conveying and heat exchanging means,

(f) feed means disposed adjacent said outer inclined member and said inner inclined member for introducing said material into said one at said low hot end, and

(g) heat producing means disposed adjacent said low hot end, having an exit portion provided with a ow cross section greater than the ow cross section of the entrance to said outer inclined member and for introducing a maximum flow of maximum temperature heated uid into said outer inclined member and said inner inclined member,

(h) a back house disposed adjacent said upper relatively cooler end, having an entrance portion provided with a flow cross section greater than the ow cross section of the exit from said outer inclined member and for providing maximum ow of maximum temperature heated Huid through said outer inclined member, said inner inclined member and said material therein,

(i) said conveying and heat exchanging means being operable to move said material to said upper relatively cooler end of said one and to function as a heat exchanger between said material and said heat,

(j) the other of said outer inclined member and said inner inclined member being adapted to receive said raw material at said upper relatively cooler end and to move said material to said low hot end.

2. The kiln recited in claim 1 wherein said inner inclined member is rotatable with said outer inclined member.

3. A rotary inclined kiln for heat treating a material and having a low hot end and an upper relatively cooler end, said kiln having:

(a) a frame,

(b) an outer inclined member rotatable on said frame,

(c) an inner inclined member disposed within said outer inclined member,

(d) a screw member on one of said outer inclined member and said inner inclined member,

(e) said screw member and said one forming a conveying and heat exchanging means,

(f) feed means disposed adjacent said outer inclined member and said inner inclined member for introducing said material into said one at said low hot end,

(g) heat producing means disposed adjacent said low hot end for introducing heat into said outer inclined member and said inner inclined member,

(l1) said conveying and heat exchanging means being operable to move said material to said upper relatively cooler end of said one and to function as a heat exchanger between said material and said heat,

(i) the other of said outer inclined member and said inner inclined member being adapted to receive said raw material at said upper relatively cooler end and to move said material to said low hot end, and

(j) drive means connected to one of said inner inclined member and said outer inclined member `for causing relative rotative movement therebetween.

4. The kiln recited in claim 3 and having drive means connected to said inner inclined member for rotating the latter with respect to said outer inclined member.

5. The kiln recited in claim 3 and having drive means connected to said outer inclined member for rotating the latter with respect to said inner inclined member.

6. A rotary inclined kiln for heat treating a material and having a low hot end and an upper relatively cooler end, said kiln having:

(a) a frame,

(b) an outer inclined member rotatable on said frame,

(c) an inner inclined member disposed within said outer inclined member,

(d) a screw member on said outer inclined member,

(e) said screw member and said one forming a conveying and heat exchanging means,

(f) feed means disposed adjacent said outer inclined member and said inner inclined member for introducing said material to said one at said low hot end, and

(g) heat producing means disposed adjacent said low hot end for introducing heat into said outer inclined member and said inner clined member,

(h) said conveying and heat exchanging means being operable to move said material to said upper relatively cooler end of said one and to function as a heat exchanger between said material and said heat,

(i) the other of said outer inclined member and said inner inclined member being adapted to receive said raw material at said upper relatively cooler end and to move said material to said low hot end.

7. A rotary inclined kiln for heat treating a material and having a low hot end and an upper relatively cooler end, said kiln having:

(a) a frame,

(b) an outer inclined member rotatable on said frame,

(c) an inner inclined member disposed within said outer inclined member,

(d) a screw member on said inner inclined member,

(e) said screw member and said one forming a conveying and heat exchanging means,

(f) feed means disposed adjacent said outer inclined member and said inner inclined member for introducing said material into said one at said low hot end, and

(g) heat producing means disposed adjacent said low hot end for introducing heat into said outer inclined member and said inner inclined member,

(h) said conveying and heat exchanging means being operable to move said material to said upper relatively cooler end of said one and to function as a heat exchange between said material and said heat,

(i) the other of said outer inclined member and said inner inclined member being adapted to receive said raw material at said upper relatively cooler end and to move said material to said low hot end.

8. A rotary inclined kiln for heat treating a material and having a lOW hot end and an upper relatively cooler end, said kiln having:

(a) a frame.

(b) an outer inclined member rotatable on said frame,

(c) an inner inclined member disposed within said outer inclined member,

(d) a screw member on one of said outer inclined member and said inner inclined member,

(e) said screw member and said one forming a conveying and heat exchanging means,

(f) feed means disposed adjacent said outer inclined member and said inner inclined member for introducing said material into said one at said low hot end, and

(g) heat producing means disposed adjacent said low hot end for introducing heat into said outer inclined member and said inner inclined member,

(h) said conveying and heat exchanging means being operable to move said material to said upper relatively cooler end of said one and to function as a heat exchanger between said material and said heat,

(i) the other of said outer inclined member and said inner inclined member being adapted to receive said raw material at said upper relatively cooler end and to move said material to said low hot end,

( j said screw member being rotatable with respect t one of said outer inclined member and said inner inclined member.

9. The kiln recited in claim 8 wherein said screw member is rotatable with respect to said inner inclined member.

10. The kiln recited in claim 8 wherein said screw member is rotatable with respect to said outer inclined member.

11. A rotary inclined kiln for heat treating a material and having a low hot end and an upper relatively cooler end, said kiln having:

(a) a frame,

(b) an outer inclined member rotatable on said frame,

(c) an inner inclined member disposed within said outer inclined member,

(d) a screw member on one of said outer inclined member and said inner inclined member,

(e) said screw member and said one forming a conveying and heat exchanging means,

(f) feed means disposed adjacent said outer inclined member and said inner inclined member for introducing said material into said one at said low hot end,

(g) heat producing means disposed adjacent said low hot end for introducing heat into said outer inclined member and said inner inclined member,

(h) said conveying and heat exchanging means being operable to move said material to said upper relatively cooler end of said one and to function as a heat exchanger between said material and said heat,

(i) the other of said outer inclined member and said inner inclined member being adapted to receive said raw material at said upper relatively cooler end and to move said material to said low hot end, and

(j) having drive means connected to said screw member for causing relative rotative movement thereof with respect to one of said outer inclined member and said inner inclined member.

12. The kiln recited in claim 1l and having drive means connected to said screw member for causing relative rotative movement thereof with respect to said inner inclined member.

13. The kiln recited in claim 1l and having drive means connected to said screw member for causing relative rotative movement thereof with respect to said outer inclined member.

References Cited UNITED STATES PATENTS 822,022 5/ 1906 Schaeffer 263-33 847,257 3/1907 Matcham 263-33 1,378,407 5/1921 Fraser 34-128 1,707,191 3/1929 Minogue 263-33 1,751,127 3/1930 Cantieny 311-128 2,887,788 5/1959 Baxter et al. 34-128 FREDERICK L. MATTESON, JR., Primary Examiner.

A. D. HERRMANN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,396,953 August 13, 1968 Dean E. sandbrook It Is certified that errorappears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2 line 29 "form" should read forming Column 3 llne 50 "dripng" should read drying Column 6 line 61 "clined" should read inclined Signed and sealed this 10th day of February 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Atteting Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 3,396,953 August 13, 1968 Dean E. Sandbrook It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line S4, "one" should read u Outer inclined member Column 7 llne 4 "one" should read inner incl ined member Signed and sealed this 22nd day of December 197D.

(SEAL) Attest;

Edward M. Fletcher, Ir. E.

ttesting Officer Commissioner 0f\. Patent@ 

